Polly Peck tycoon Asil Nadir fled Britain because he was a broken man with no hope of a fair trial over allegations that he stole nearly £150m from the collapsed firm, the Old Bailey heard .

Nineteen years after he left for Northern Cyprus, the 71-year-old broke his silence as he took the stand in his fraud trial.

Nadir told the jury he left Britain on 4 May 1993 after his mental health collapsed, he was accused of trying to bribe a judge, and believed his post had been tampered with. Denying all charges, he said: "By the time I left the UK, I was a totally broken man. My health was in tatters, my hope on a fair trial was in tatters. I had zero hope of receiving a fair trial."

Asked by his lawyer, Philip Hackett QC, how his health had been affected, he added: "I was not well. Half way through the proceedings in early 1992 I was getting very unwell and the judge, Justice Tucker, made a ruling that I should see a psychiatrist and should have treatment. All through my life up to that point I had been in excellent health."

The court was also told about the "frightening situation" Nadir found himself in after he was accused of trying to bribe his original trial judge.

His lawyer read a transcript from a pre-trial hearing in November 1992 when the conspiracy allegations, which were later dropped, were first put to Nadir, his lawyer Anthony Scrivener QC, and Justice Tucker – who were both implicated.

Denying any involvement in a conspiracy, Nadir said: "It was a frightening situation. I still remember the concerns and the fear the lordship [Justice Tucker] had in his face. I had laid all my hopes on getting an independent trial but was very worried I would not. The judge's expression is not one that one wants to see."

He added: "Anthony Scrivener QC turned to me and said he was extremely worried about it. He tried to get me to give him permission to get him [Scrivener] off the case [but] I didn't give him permission."

The businessman's evidence was heard on the first day of the defence's case in a trial that started in January. It is the first time Nadir has taken the stand since he voluntarily returned from exile in his native Northern Cyprus in 2010.

The court heard that he believed private letters had been tampered with after his post appeared to have been opened, leading to a private detective being hired to investigate. He said: "I did have concerns that my mail was being intercepted. I was not getting mail in the normal way people get mail. Every now and then I would have a pile of opened envelopes with a plastic band wrapped around them."

Nadir explained to the court that he had started his life in business as a six-year-old selling newspapers in his home town. He arrived in the UK in 1980 and bought the then small textile firm Polly Peck, which had a turnover of £2m. He turned it into a conglomerate worth £2bn.

Explaining to the court why he had moved money to a Cyprus-based subsidiary, he claimed this was because he could get a higher rate of interest from the Mediterranean island's banks.

He added that many Cypriots, from both the Greek and Turkish sectors of the island, wanted to invest in the company.

"I have seen dozens of Greek Cypriots on the register of PPI [Polly Peck] because they saw how successful it was from their neighbours. It was very attractive for them to invest in those shares."

But by 1991 Nadir was declared personally bankrupt, he was sued by Polly Peck administrators, and could no longer afford his own lawyers in civil actions, the court heard.

On Tuesday, he claimed the company, which went bust in 1990, was not insolvent. "I think it had a tremendous future and this attitude was shared by the top brokers and investors in this country and worldwide. Finance was available from Turkey. The amount discussed was £70m to obtain a standstill [agreement].

"The finance was from three top Turkish banks on the instigation of the president of Turkey. It was a committed financial arrangement."

The Serious Fraud Office, which is prosecuting the case, claims Nadir abused his power as chairman and chief executive of Polly Peck. The case against him alleges that he "helped himself to tens of millions of pounds" of Polly Peck's money in transfers of more than £146m. The jury previously heard Nadir used the money to secretly buy shares to support the firm's share price and buy expensive properties for himself and relatives.

Staying in his Mayfair home in central London under strict bail conditions, he is set to give more evidence on Wednesday. The trial continues.